Light deflection apparatus

ABSTRACT

A deflection apparatus deflects a light beam in accordance with the characteristics of energizing signals to provide a trace of those signal characteristics on a display medium. The assembly includes a plurality of suspension galvanometers each having a coil responsive to an associated one of the signals to deflect a mirror positioned in the path of the light beam which in turn deflects the light beam. The galvanometers are suspended on a rigid supporting structure which is self-aligning. Pole pieces have a plurality of teeth which define secondary air gaps and provide a substantially constant, concentrated flux field for each of the coils. A printed circuit board cooperates with cover members to form a dust free enclosure.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to light deflection mechanismsand more specifically to galvanometers of the type used in anoscillograph for providing a permanent record of a plurality ofenergizing signals introduced to the galvanometers.

2. Description of the Prior Art

An oscillograph is an instrument having a light source providing a beamof light and a photosensitive paper movable in the path of the beam oflight and having photosensitive properties responsive to the beam oflight to provide a trace on the paper. A galvanometer assembly,positioned between the light source and the photosensitive paper in thepath of the beam of light, includes a mirror which deflects the beam oflight in a direction transverse to the movement of the paper. Thedeflection of the mirror is in accordance with the characteristics of anenergizing signal introduced to the galvanometer. Thus the greater themagnitude of the signal, the greater the deflection of the light beam.As the light beam is deflected, it provides the trace on thephotosensitive paper with characteristics representative of thecharacteristics of the energizing signal.

The galvanometer assembly typically includes a coil which is suspendedwith the mirror between a pair of wires. The coil is positioned withinan air gap defined by pole pieces attached to a large permanent magnet.The coil is energized through the suspending wires by the energizingsignal to be recorded. This signal produces an electromagnetic effect inthe coil which aids or opposes the magnetic field produced by thepermanent magnet to deflect the coil and the attached mirror. Agalvanometer assembly of this type is disclosed and claimed byRichardson in his U.S. Pat. No. .[.3,599,611,.]. .Iadd.2,599,661.Iaddend.assigned of record to the assignee of record of the presentapplication.

In the past, each of the galvanometers have been separately constructedand encased. Each galvanometer has been provided with its own secondarypole pieces which have registered with grooves in a pair of primary polepieces associated with the permanent magnet. As a result of thisindividual construction, the cost per channel of the galvanometerassembly has been relatively high. In addition, each of thegalvanometers has been separately mounted so that any alignment of thegalvanometers with respect to each other has been carried out by theuser rather than the manufacturer. In some cases, the coils associatedwith the galvanometers have been mounted in tubes filled with oil. Inthis configuration, the oil has tended to damp any undesirableoscillations of the coil and mirror. A heater assembly has been used tomaintain the temperature of the oil so that its viscosity tends toremain substantially constant.

Although these oscillographs and galvanometer assemblies have providedexcellent means for recording signals, it is always desirable tominimize the cost per channel. In addition, it may be desirable toprovide means for simultaneously aligning all of the galvanometers in asingle oscillograph.

SUMMARY OF THE INVENTION

In accordance with the present invention, a galvanometer assembly isprovided which is particularly adapted for modular construction. Thisparticular assembly includes more than one galvanometer, and in fact mayinclude any number of galvanometers depending on the intended use of theassembly. In addition to providing a cost per channel which is reducedby as much as 50%, this assembly provides a single multi-channel modulewhich can be prealigned at the factory. In addition, the module can bemounted in an oscillograph in a manner providing for the simultaneousalignment of the channels in the assembly. The modular construction alsomakes it relatively easy to maintain the ambient temperature of thegalvanometers. Furthermore, common pole pieces provide substantially thesame flux per channel so that the channels have similar performancecharacteristics.

Each of the galvanometer channels is provided with a coil and a mirrorwhich are suspended between wires supported by a structure including atop fixture number and a bottom fixture member. These fixture membersare maintained in a fixed, spaced relationship by rod members whichextend through the fixture members. Pointed set screws in the fixturemembers register with aperatures in the rod members to provide forself-alignment of the supporting structure.

A pair of secondary pole pieces are provided on opposite sides of thecoils in the galvanometers. Each of the pole pieces is separatelyattached to the rod members and includes a plurality of teeth each ofwhich extends into proximity with an associated one of the coils. Withthe provision of pole pieces which are common to all of thegalvanometers, the flux per channel is maintained substantially constantso that the deflection characteristics of the individual channels aresimilar.

It has also been found particularly advantageous that the galvanometerscan all be encased in a single enclosure. This facilitates maintenanceof the ambient temperature of the galvanometers at a substantiallyconstant level to minimize any differences in performancecharacteristics which might otherwise result.

These and other features and advantages of the invention will be moreapparent with a description of preferred embodiments and a discussion ofthe associated drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of an oscillograph including aplurality of galvanometers each responsive to a different energizingsignal to provide an associated trace on a photosensitive medium;

FIG. 2 is a front elevational view of one form of a galvanometerassembly of the present invention illustrating a galvanometer module, anassociated permanent magnet assembly, and a heater assembly;

FIG. 3 cross sectional elevational view of the galvanometer assemblytaken along lines 3--3 of FIG. 2;

FIG. 4 is a top plan view of the galvanometer assembly illustrated inFIG. 2;

FIG. 5 is a front elevational view partially in section of one form of apreferred embodiment of the galvanometer module of the presentinvention;

FIG. 6 is a cross sectional view of the galvanometer module taken alonglines 6--6 of FIG. 5;

FIG. 7 is an enlarged side elevational view partially in section of oneof the galvanometers associated with the module illustrated in FIG. 5;

FIG. 8 is a schematic diagram of the heater assembly illustrated in FIG.2;

FIG. 9 is an axial cross sectional view of a bottom terminal assemblyassociated with the galvanometer illustrated in FIG. 7;

FIG. 10 is an axial cross sectional view of a top terminal assemblyassociated with the galvanometer illustrated in FIG. 7; and

FIG. 11 is an enlarged axial cross sectional view of a portion of thetop terminal assembly illustrated in FIG. 10.

DESCRIPTION OF PREFERRED EMBODIMENTS

A recording oscillograph is an instrument which deflects a light beam inaccordance with the characteristics of a signal and then records thedeflections of the light beam. Usually there will be several signalseach deflecting an associated light beam in a multi-channel instrument.Such an oscillograph is illustrated schematically in FIG. 1 anddesignated generally by the reference numeral 11. The oscillograph 11includes a light source such as an argon or xenon lamp 13 which providesa beam of light 15. The oscillograph 11 may include a series of lensescollectively referred to as a window 17 for shaping the beam of light 15in order to provide an incident light beam 16.

This incident light beam 16 is directed onto a light deflectionmechanism such as a galvanometer assembly designated by the referencenumeral 25. In the galvanometer assembly 25, a plurality ofgalvanometers 23 each includes a mirror 21 which is positioned in thepath of the incident light beam 16. When the incident light beam 16strikes the mirrors 21, a plurality of reflected light beams 27 areproduced, one for each of the galvanometers 23.

These reflected light beams 27 are projected onto a photosensitivemedium, such as a photosensitive paper 29. The paper 29, which istypically moved at a constant rate of speed by a motor 31, hasphotosensitive properties so that each of the reflected light beams 27produces a trace 33 on the paper 29.

Each of the galvanometers 23 is responsive to an associated signal to berecorded to rotate the associated mirrors 21 slightly. Of course thisproduces a corresponding movement of the associated reflective lightbeam 27 with respect to the paper 29. The degree of movement isdependent upon the magnitude of the signal to be recorded so that theresulting trace 33 provides an indication of the characteristics of therecorded signal.

Each of the galvanometers 23 includes a coil 41 which is connected to anassociated one of the mirrors 21 and disposed in a substantiallyconstant magnetic field. The signal to be recorded is introduced to thiscoil 41 and the resulting electromagnetic effect either aids or opposesthe constant magnetic field to provide a corresponding rotation of thecoil 41. This rotation is transferred to the associated mirror 21 toprovide the desired deflection of the associated reflected light beam27.

This function can be more easily understood by referring to anembodiment of one form of the galvanometer assembly 25 of the presentinvention as illustrated in FIGS. 2, 3 and 4. This galvanometer assembly25 comprises a permanent magnet assembly 43, a heater assembly 45, and agalvanometer module 47 which includes the galvanometers 23.

The permanent magnet assembly 43 includes a bipolar permanent magnet 49preferably having a horseshoe configuration. Each of the poles of thepermanent magnet 49 is provided with a primary pole piece 51, 53 bestillustrated in FIG. 3. These primary pole pieces 51 and 53 are directedtoward each other to produce a primary air gap 55 within which thegalvanometer module 47 is positioned to provide the substantiallyconstant magnetic field in proximity to the galvanometers 23.

The permanent magnet 49 can be made from any suitable material such asAlnico-5 which is commonly available from many magnetic materialsuppliers such as Arnold Engineering Company of Marengo, Illinois. In apreferred embodiment, the material of the primary pole pieces 51 and 53is a low carbon, free machining steel.

The galvanometer module 47 is separately illustrated in FIGS. 5 and 6.Although the module 47 is illustrated to include four of thegalvanometers 23, it will be understood that it may include any numberof galvanometers, but preferably more than one in order to achieve theadvantage of a reduced cost per channel.

The galvanometers 23 are supported by a structure including a topfixture member 61 and a bottom fixture member 63 which are maintained ina spaced, fixed relationship by a pair of rod members 65. The rodmembers 65, which may have a parallel relationship, are preferablyspaced apart to provide the supporting structure with a generally rigidconfiguration. In a preferred embodiment, the top and bottom fixturemembers 61 and 63, .[.respectfully.]. .Iadd.respectively.Iaddend., areformed from non-magnetic metal and are drilled to produce rod holes 67of a diameter suitable to accept the rod members 65.

The rod members 65, which may also be formed from non-magnetic metal,can be drilled to produce alignment holes 69. When the rod members 65are operatively positioned with respect to the fixture members 61 and63, the alignment holes 69 preferably extend within and laterally of theassociated rod holes 67.

At a corresponding position in the top and bottom fixture members 61 and63 respectively, set screw holes 71 can be provided to extend laterallyof the rod hole 67. Each of the screw holes 71 can be suitably threadedto receive a pointed set screw 73 which registers with the associatedalignment hole 69 in the associated rod member 65 to automatically alignthe supporting structure.

The resulting configuration for the supporting structure is particularlydesirable. It provides a structure which is quite rigid and yet easy toassemble and align. The rigidity is particularly desirable in order toprovide the galvanometers 23 with a solid basis for support. Thestructure is particularly easy to assemble and align. By merelyinserting the rod member 65 into the associated rod hole 67 andtightening the associated set screw 73, the rod members 65 areautomatically positioned with respect to the top and bottom fixturemembers 61 and 63 respectively. This particular structure with its easeof assembly and self-aligning characteristics significantly reduces thecost per channel of the module 47.

A preferred embodiment of one form of the galvanometers 23 is bestillustrated in the assembly in FIG. 3, in the module in FIG. 5, andseparately in FIG. 7. With particular reference to FIG. 5, it can beseen that each of the galvanometers 23 is associated with one of aplurality of holes 77 in the top fixture member 61 and one of aplurality of holes 79 in the bottom fixture member 63. In a preferredembodiment, each of the holes 77 is coaxially aligned with an associatedone of the holes 79.

Generally speaking, each of the galvanometers 23 comprises a suspensionwhich is supported under tension between an upper terminal assembly 81and a lower terminal assembly 83. The upper terminal assembly 81 isdisposed on the side of the associated hole 77 opposite the associatedgalvanometer 23 but is sufficiently large to avoid being pulled throughthe hole 77. Similarly, the lower terminal assembly 83, which isdisposed on the side of the lower fixture member 63 opposite thegalvanometer 23, is larger than the associated hole 79.

In a preferred embodiment, the suspension associated with each of thegalvanometers 23 includes an upper wire 91 which is electricallyconnected to a tube 93 (FIG. 7) which is in turn electrically connectedto one end of the associated coil 41. The opposite end of the coil 41 iselectrically connected to a bottom wire 95 which is electricallyterminated at the lower terminal assembly 83. In a preferred embodiment,the tube 93 is adapted to receive the upper wire 91 along the axis ofthe tube 93 at which point it can be soldered to provide structural andelectrical support. The tube 93 can be axially slotted to produce agroove 97 having an increased surface area for receiving the associatedmirror 21. The mirror 21 can be glued in this position as illustrated inFIG. 7.

The coil 41, which comprises many turns of fine wire, can be woundaround a pair of spaced apart sapphire jewels 99 to provide the coil 41with a longitudinal configuration and circular cross section. In theembodiment of FIG. 7, a stirrup ribbon 101 is threaded around one of thejewels 99 and through the coil 41 at the upper end thereof. The ends ofthe ribbon 101 are positioned along either side of tube 93 at the lowerend thereof. The stirrup ribbon 101 together with one end of the wirefrom the coil 41, are physically bound to the lower end of the tube 93by a wrapping wire 103. This junction is preferably soldered to providephysical and electrical continuity between the tube 93 and the coil 41.The opposite end of the coil can be similarly electrically andstructurally attached to the lower wire 95.

As best illustrated in FIG. 3 the galvanometer module 47 is positionedso that the coils 41, which are preferably in planar alignment in themodule 47, are disposed within the primary air gap 55 formed between theprimary pole pieces 51 and 53. In this location, the coils 41 aresubjected to a substantially constant magnetic field produced by thepermanent magnet assembly 43. The signal to be recorded can then beintroduced across the upper and lower terminal assemblies 81 and 83 toenergize the associated coil 41. Thus energized, the coil will produceits own magnetic field which either aids or opposes the constantmagnetic field associated with the permanent magnet assembly 43. Sincethe electromagnetic field associated with the coil 41 will have amagnitude dependent upon the magnitude of the signal to be recorded, thecoil 41 will tend to rotate about its longitudinal axis in accordancewith the magnitude of the energizing signal. This rotation will betransferred through the tube 93 to the mirror 21 which will provide acorresponding deflection in the associated reflected beam 27.

In order to concentrate the flux associated with the magnetic field ofthe permanent magnet assembly 43, a pair of secondary pole pieces 107and 109, best illustrated in FIG. 6, are provided in a preferredembodiment. The secondary pole pieces 107 and 109 are preferably insurface contact with the pole pieces 51 and 53 respectively to receivethe magnetic flux associated with the permanent magnet assembly 43.

This flux is concentrated into a plurality of teeth 111 in the secondarypole piece 107 and a plurality of teeth 113 in the secondary pole piece109. One of the teeth 111 and one of the teeth 113 are associated witheach of the galvanometers 23. These teeth 111 and 113 have a generallylongitudinal configuration and extend laterally of the respectivesecondary pole piece 107 and 109 substantially parallel to and inproximity with the associated coil 41. Thus the teeth 111 and 113associated with the coils 41 face each other on opposite sides of thecoils 41 to produce a plurality of secondary air gaps 114 within each ofwhich an associated one of the coils 41 is positioned.

In a preferred embodiment, the secondary pole pieces 107 and 109 areattached to the rod members 65 by a plurality of screws 115 which extendinto threaded holes in the rod members 65. The secondary pole pieces canbe formed from any low carbon, free machining steel.

As the signal to be recorded is applied to the associated coil 41, therotational movement of the coil 41 is opposed by the tortionalresistance of the wires 91 and 95. Thus, the suspension will follow thesingle degree of freedom phenomenon well known to those skilled in theart. For this reason, damping may be desired in order to obtain usableresults over a wide range of operating frequencies. In a preferredembodiment, damping is provided for each of the galvanometers 23 by afluid filled tube 121 which extends around the associated coil 41. Thefluid can be any non-volatile liquid, such as oil 122, having aviscosity which opposes the movement of the coil 41.

The tubes 121 are preferably aligned coaxially with the suspensionforming the associated galvanometer 23. One means of maintaining thisalignment comprises a plurality of centering guides or wires 139 whichcan be attached to the pole piece 109 to extend across an associated oneof the secondary air gaps 114 formed between the opposing teeth 111 and113. The wires 139 are preferably attached to the pole piece 109 by anadhesive or glue. As illustrated in the embodiment of FIG. 6, the wires139 can be wrapped around the upper end of the associated tube 121 tomaintain its coaxial alignment with the associated coil 41 of theassociated galvanometer 23.

The amount of damping provided by the fluid filled tubes 121 isdependent upon the viscosity of the oil 122. Since this viscositychanges with temperature, it may be desirable in some applications tomaintain the environment of the galvanometers 23 at a substantialconstant temperature. This is a main purpose of the heater assembly 45which is best illustrated in FIGS. 2 and 4.

The heater assembly 45 in the illustrated embodiment includes threeheater blocks 125, 126, and 127. The heater block 125 can be attached tothe primary pole pieces 51 and 53 by a plurality of screws 128.Similarly, the heater blocks 126 and 127 can be attached to the primarypole pieces 51 and 53 by a plurality of screws 130. Holes 132 can bedrilled and threaded in each of the heater block members 125, 126 and127 to provide means for mounting the galvanometer assembly 25 in theoscillograph 11.

The blocks 125, 126 and 127 can be electrically heated by a circuitillustrated in FIG. 8 the elements of which are shown best in FIGS. 2and 4. The primary heating elements in this circuit include resistors129, 131 and 133 which are serially connected and energized with theclosing of a thermostat 135. A capacitor 137 can be connected inparallel with the thermostat 135, to provide means for inhibiting anyburning of the contacts associated with the thermostat 135. The resistor129, which may be 250 ohms and 25 watts, can be attached to the block125 along with the capacitor 137 and the thermostat 135. The resistors131 and 133, which may each be 50 ohm and 5 watts, each can be attachedto the respective blocks 126 and 127.

The bottom terminal assembly 83, illustrated generally in FIGS. 3 and 5and in greater detail in FIG. 9, has at least two purposes. It providesan electrical terminal for the wire 95 which energizes the coil 41, andit provides a structural terminal for opposing the tension on thesuspension. In a preferred embodiment illustrated in FIG. 9, a metalterminal 143 is soldered to the wire 95. This terminal 143 is providedwith a plug 145 which can be seated in the bottom of the associated tube121. A flange 147 can be attached to the tube 121 and the terminal 143by a suitable adhesive such as resin 149. The flange 147 provides ashoulder 151 which is positioned against the lower fixture member 63 buthas a diameter greater than that of the associated hole 79 so that itopposes the tension on the suspension. Since the tube 121 extendsthrough the entire hole 79 in the illustrated embodiment, the wire 95and terminal 143 are insulated from the lower fixture member 63.

The upper terminal assembly 81 is best illustrated in FIGS. 10 and 11.The upper terminal assembly 81 provides means for opposing the tensionon the suspension, means for insulating the wire 91 from the top fixturemember 61, and means for rotationally aligning the suspension.

The assembly 81 includes a sleeve 155 which has insulating propertiesand is glued within an associated one of the holes 77 in the top fixturemember 61. The sleeve 155 is provided with a flange 157 which ispositioned on the side of the top fixture member 61 opposite the mirror21 and coil 41. The flange 157 has a diameter greater than that of thehole 77 so that it is incapable of moving through the hole 77.

A sleeve 159 is positioned within the sleeve 155 and has a shoulder 161which is glued to the flange 157 on the sleeve 155. At the opposite endof the sleeve 159, a plurality of friction fingers 163 engage a metalterminal 165 which extends entirely through the sleeve 159. The frictionfingers 163 aid in centering the metal terminal 165 but do not inhibitrotation of the terminal 165 relative to the sleeve 159. The terminal165 can have a cylindrical configuration and can be threaded at thelower end thereof as illustrated in FIG. 10. A washer 167, preferablyhaving a diameter greater than that of the sleeve 159 but less than thatof the sleeve 155 is positioned over the threaded end of the terminal165. A nut 169 holds the washer 167 in place and inhibits the upperwardmovement of the terminal 165 with respect to the sleeves 155 and 159.

An enlarged FIG. 11 illustrates that the flange 161 associated with thesleeve 159 can be provided with an upwardly extending shoulder 171 whichcooperates with a downwardly extending shoulder 173 on a stopping flange175. The flange 175 can be fixed to the terminal 165 by a set screw 177.

The shoulders 171 and 173 permit rotation of flange 175 relative to theflange 161 over a predetermined angular displacement. The extent of theangular displacement, which in a preferred embodiment is 45°, isdependent upon the placement of the shoulders 171 and 173. Since theflange 175 has a fixed relationship to the wire 91 and the flange 161has a fixed relationship to the top fixture member 61, this rotationpermits alignment of the mirror 21 with respect to the supportingstructure.

When the galvanometers 23 are first constructed, tension can be appliedto the assembly by drawing the wire 91 through a small tube 179 which issoldered to the upper end of the wire 91 as shown in FIG. 10. A desiredtension can be applied to the tube 179 and hence to the wire 91 as thetube 179 is soldered to the terminal 165. This tension on the wire 91can be maintained by coiling the wire 91 to form a spring 180. Thetension on the wire 91 is opposed by the stopping flange 175 which isfixed to the terminal 165 and therefore inhibits its downward movementin FIG. 9.

In a preferred embodiment, the galvanometer module 47 has an enclosurewhich provides dust protection for the galvanometers 23. An upperenclosure member 181, and a lower enclosure member 182, best illustratedin FIG. 3, extend over the top, the sides, and a substantial portion ofthe front of the galvanometers 23 and supporting structure. The upperenclosure member 181 can be fixed to the supporting structure by aplurality of screws 183 which extend into threaded holes in the upperfixture member 61. Similarly, screws 187 can be provided to fix thelower enclosure member 182 to the lower fixture member 63.

The enclosure members 181 and 182 define a window 188 at the front ofthe module 47, as shown in FIG. 2. A bezel 189, which can be held inplace by the screws 183, supports a transparent pane 191 over thiswindow 188. In a preferred embodiment, both the incident and reflectedbeams of light 19 and 27, respectively, pass through the pane 191 to themirrors 21.

The pane 191 is preferably disposed at an angle such as 6° with respectto the beams of light 16 and 27 so that any ghosts associated with thebeams are cast away from the photosensitive paper 29. This feature canbe further enhanced by the provision of an anti-glare coating on thepane 191.

Although the enclosure members 181 and 182 can be formed as a singleelement, the bifurcated construction may be preferred since it permitsaccess to the galvanometers 23 with removal of only a small portion ofthe enclosure. For example, the ease with which the top enclosure member181 can be removed with be particularly appreciated if the damping fluidsuch as the oil 122, is to be changed.

The enclosure associated with the module 47 can be completed by aprinted circuit board 192 which cooperates with the enclosure members181 and 182 to substantially enclose the galvanometers 23 and supportingstructure. The circuit board 192 can be held in place along the back ofthe module 47 by a plurality of screws 194 which extend into the upperand lower fixture members 61 and 63 respectively. A pair of wires 193and 195 can be used to connect the terminals 165 and 143 respectively tothe circuit board 192. The circuit board 192 preferably extends beyondthe side of the enclosure members 181 and 182 to facilitate itsregistration with a terminal strip 197, best shown in FIG. 4.

From the foregoing discussion it is apparent that the galvanometerassembly of the present invention offers many significant advantages.First, it lends itself readily to use in an oscillograph having modularconstruction. With the provision of several of the galvonometers 23 in asingle module 47 the cost per channel of the assembly 25 is greatlyreduced, for example, by as much as 50 percent. The modular constructionalso makes it possible to align the galvanometers 23, both individuallyand with respect to each other, at the factory.

A single enclosure for several of the galvanometers 23 makes it possibleto provide a single pane 191 which is relatively large in size andtherefore easier to clean.

With the provision of only a single pair of secondary pole tips 107,109, the flux per channel is substantially constant. This flux isconcentrated in proximity to the coils 41 by the teeth 111 and 113.

Although the invention has been described with reference to specificembodiments, it will be understood that it can be otherwise embodied sothat the scope of the invention should be ascertained only in referenceto the following claims.

We claim:
 1. A light deflection mechanism responsive to a plurality ofenergizing signals to provide on display means a plurality of traceseach representative to the characteristics of an associated one of theenergizing signals, the mechanism comprising:a first structural memberhaving portions defining a plurality of first apertures; a secondstructural member disposed relative to the first structural member andhaving portions defining a plurality of second apertures each extendingin alignment with an associated one of the first apertures in the firststructural member; means for maintaining the first and second structuralmembers in a spaced relationship; a plurality of light deflectors eachextending through an associated one of the first apertures of the firststructural member and an associated one of the second apertures in thesecond structural member; first means for engaging the light deflectorson the side of the first apertures opposite the light deflectors; secondmeans for engaging the light deflectors on the side of the secondaperture opposite the light deflectors; the second means cooperatingwith the first means to provide the deflectors with a tensile stressbetween the first structural member and the second structural member;and each of the light deflectors including a mirror providing areflected light beam and a coil responsive to the associated energizingsignal to deflect the coil and the mirror so that the reflected lightbeam provides the associated trace representative of the characteristicsof the associated energizing signal.
 2. The mechanism set forth in claim1 wherein the means for maintaining the first structural member and thesecond structural member in the spaced relationship includes:a thirdstructural member extending between the first structural member and thesecond structural member; and a fourth structural member extendingbetween the first structural member and the second structural member inspaced relationship with the third structural member, and; the fourthstructural member cooperating with the third structural member tomaintain the first structural member and the second structural member inthe spaced relationship.
 3. The mechanism recited in claim 2 furthercomprising:portions of the first structural member defining a first pairof openings; portions of the second structural member defining a secondpair of openings; the third structural member having a first endsupported in an associated one of the first pair of openings and asecond end supported in an associated one of the second pair ofopenings; the fourth structural member having a first end supported inthe other of the first pair of openings and a second end supported inthe other of the second pair of openings; a plurality of set screws eachextending through an associated one of the first and second structuralmembers transversely of the associated third and fourth structuralmembers into an associated one of the first and second pair of openingsfor engaging the associated third and fourth structural members; wherebythe first and second structural members are fixed to the ends of thethird and fourth structural members by the set screws to maintain thefirst and second structural members in the space relationship.
 4. Themechanism set forth in claim 3 further comprising:portions of the thirdstructural member defining a pair of slots separated from each other bya predetermined distance; and the set screws associated with the thirdstructural member extending into the associated first and secondopenings in the associated first and second structural members and intothe associated slots in the third structural member to maintain thefirst and second structural members in a relationship spaced by adistance dependent upon the predetermined distance.
 5. The lightdeflection mechanism recited in claim 1 further comprising:enclosuremeans forming a single cavity and a plurality of light deflectors beingat least partially disposed within the single cavity of the enclosuremeans; and means for attaching the enclosure means to at least one ofthe first and second structural members and the means for maintainingthe first and second structural members in a spaced relationship.
 6. Thelight deflection mechanism recited in claim 5 wherein the enclosuremeans includes a single windowpane through which the light passes to andfrom the plurality of light deflectors. .[.7. A galvanometer assemblyadapted for use with a magnet in deflecting a light beam in accordancewith the characteristics of a plurality of signals to record the signalson a photosensitive medium, including:a plurality of suspensiongalvanometers each having an electrical coil adapted to receive anassociated one of the signals and a mirror disposed in the path of thelight beam and movable with the associated coil to deflect the lightbeam in response to the characteristics of the associated signal;supporting structure means for suspending the plurality galvanometerswith the coils of the galvanometers disposed in substantially planaralignment; flux concentration means associated with the magnet andhaving a plurality of teeth for concentrating the magnetic flux of themagnet in proximity to the coils of the galvanometers; and means forattaching the flux concentration means to the supporting structure..].8. The galvanometer assembly recited in claim .[.7.]. .Iadd.10.Iaddend.wherein the flux concentration means includes:a first polepiece associated with the magnet and having a plurality of first teetheach extending into proximity to an associated one of the coils of anassociated one of the galvanometers, the first teeth being disposed insubstantial alignment along one side of the galvanometers; and a secondpole piece associated with the magnet and having a plurality of secondteeth each extending into proximity to an associated one of the coils ofan associated one of the galvanometers, the second teeth being disposedin substantial alignment along the side of the galvanometers oppositethe first teeth.
 9. .[.The galvanometer assembly recited in claim 7wherein the supporting structure includes:a top fixture member;.]..Iadd.A galvanometer assembly adapted for use with a magnet indeflecting a light beam in accordance with the characteristics of aplurality of signals to record the signals on a photosensitive medium,including: a plurality of suspension galvanometers each having anelectrical coil adapted to receive an associated one of the signals anda mirror disposed in the path of the light beam and movable with theassociated coil to deflect the light beam in response to thecharacteristics of the associated signal; supporting structure means forsuspending the plurality galvanometers with the coils of thegalvanometers disposed in substantially planar alignment; fluxconcentration means associated with the magnet and having a plurality ofteeth for concentrating the magnetic flux of the magnet in proximity tothe coils of the galvanometers; and means for attaching the fluxconcentration means to the supporting structure; said supportingstructure means including .Iaddend. a bottom fixture member disposed inspace relationship to the top fixture member; .[.rod.]. means formaintaining the top fixture member and the bottom fixture member inspaced relationship; and means for suspending the plurality ofgalvanometers between the top fixture member and the bottom fixturemember.
 10. .[.The galvanometer assembly recited in claim 7 furthercomprising:.]. .Iadd.A galvanometer assembly adapted for use with amagnet in deflecting a light beam in accordance with the characteristicsof a plurality of signals to record the signals on a photosensitivemedium, including:a plurality of suspension galvanometers each having anelectrical coil adapted to receive an associated one of the signals anda mirror disposed in the path of the light beam and movable with theassociated coil to deflect the light beam in response to thecharacteristics of the associated signal; supporting structure means forthe plurality of galvanometers, said supporting structure meansincluding a top fixture member and means for suspending the plurality ofgalvanometers from said top fixture member, with the coils of thegalvanometers disposed in substantially planar alignment; fluxconcentration means associated with the magnet and having a plurality ofteeth for concentrating the magnetic flux of the magnet in proximity tothe coils of the galvanometers; means for attaching the fluxconcentration means to the supporting structure; .Iaddend. a window panehaving a planar configuration and being disposed in the path of thelight beam; and bezel means for supporting the window pane in a fixedrelationship with the supporting structure with the plane of the windowpane having an angular relationship with the beam of light passingthrough the window pane so as to cast any ghosts associated with thebeam of light away from the galvanometers.
 11. .[.The galvanometerassembly recited in claim 7, further comprising;.]. .Iadd.A glavanometerassembly adapted for use with a magnet in deflecting a light beam inaccordance with the charateristics of a plurality of signals to recordthe signals on a photosensitive medium, including:a plurality ofsuspension galvanometers each having an electrical coil adapted toreceive an associated one of the signals and a mirror disposed in thepath of the light beam and movable with the associated coil to deflectthe light beam in response to the characteristics of the associatedsignal; supporting structure means for the plurality of galvanometers,said supporting structure means including a top fixture member and meansfor suspending the plurality of galvanometers from said top fixturemember, with the coils of the galvanometers disposed in substantiallyplanar alignment; flux concentration means associated with the magnetand having a plurality of teeth for concentrating the magnetic flux ofthe magnet in proximity to the coils of the galvanometers; means forattaching the flux concentration means to the supporting structure;.Iaddend. terminal means included in the galvanometers for introducingthe signals to the coils of the galvanometers; a circuit board attachedto the supporting structure for introducing the signals to the terminalmeans; and enclosure means formed in part by the circuit board forenclosing at least the galvanometers to provide dust protection for thegalvanometers.
 12. A galvanometer module adapted for use with a magnetfor deflecting a light beam in accordance with the characteristics of aplurality of signals to record the signals on a display medium,including:a supporting structure; a first galvanometer coupled to thesupporting structure having a first electrical coil adapted to receive afirst one of the signals and a first mirror coupled to the first coiland deflectible with the first coil in response to the characteristicsof the first signal, the first mirror being disposed in the path of thelight beam and deflecting the light beam in accordance with thecharacteristics of the first signal; a second galvanometer coupled tothe supporting structure and having a second electrical coil adapted toreceive a second one of the signals and a second mirror coupled to thesecond coil and deflectible with the second coil in response to thecharacteristics of the second signal, the second mirror being disposedin the path of the light beam and deflecting the light beam inaccordance with the characteristics of the second signal; the firstgalvanometer and the second galvanometer having a generally longitudinalconfiguration and being disposed in a relatively planar relationship; asingle enclosure coupled to the supporting structure and defining asingle cavity substantially enclosing the first galvanometer and thesecond galvanometer; whereby the light beam directed onto the firstmirror and the second mirror is deflected to provide on the displaymedium a display of the characteristics of the respective first signaland second signal.[...]..Iadd.; said supporting structure including:atop fixture member; a bottom fixture member; means for maintaining saidtop and bottom fixture members in a spaced relationship; and means forsuspending the first galvanometer and the second galvanometer eachbetween the top fixture member and the bottom fixture member. .Iaddend..[.13. The galvanometer module recited in claim 12 wherein thesupporting structure includes:a first fixture member; a second fixturemember; means for maintaining the first fixture member and the secondfixture member in a spaced relationship; and the first galvanometer andthe second galvanometer each being suspended between the first fixturemember and the second fixture member..].
 14. The galvanometer module setforth in claim 12 wherein the enclosure of the module is coupled to thesupporting structure and substantially encloses the supporting structureas well as the first and second galvanometers. .[.The galvanometermodule set forth in claim 12 wherein the enclosure includes:.]. .Iadd.Agalvanometer module adapted for use with a magnet for deflecting a lightbeam in accordance with the characteristics of a plurality of signals torecord the signals on a display medium, including:a supportingstructure; a first galvanometer coupled to the supporting structurehaving a first electrical coil adapted to receive a first one of thesignals and a first mirror coupled to the first coil and deflectiblewith the first coil in response to the characteristics of the firstsignal, the first mirror being disposed in the path of the light beamand deflecting the light beam in accordance with the characteristics ofthe second signal; the first galvanometer and the second galvanometerhaving a generally longitudinal configuration and being disposed in arelatively planar relationship; a single enclosure coupled to thesupporting structure and defining a single cavity substantiallyenclosing the first galvanometer and the second galvanometer; wherebythe light beam directed onto the first mirror and the second mirror isdeflected to provide on the display medium a display of thecharacteristics of the respective first signal and second signal; saidenclosure including: .Iaddend. a first enclosure member having a fixedrelationship with the supporting structure, the first enclosure memberbeing removable from the supporting structure to provide access to thefirst and second galvanometers; a second enclosure member having a fixedrelationship with the supporting structure and defining with the firstenclosure member a window; and a single window pane having an inclinedrelationship with respect to the plane of the first galvanometer and thesecond galvanometer; and the light beam passing to and from the firstand second mirrors through the window pane. .[.16. A galvanometerassembly adapted for use with a bipolar magnet in deflecting a lightbeam in accordance with the charateristics of a plurality of signals torecord the signals on a photosensitive medium, including: a plurality ofsuspension galvanometers each having an electrical coil adapted toreceive an associated one of the signals and a mirror disposed in thepath of the light beam and movable with the associated coil to deflectthe light beam in response to the characteristics of the associatedsignal; supporting structure means for suspending the plurality ofgalvanometers with the coils of the galvanometers disposed insubstantially planar alignment; a first pair of pole pieces disposed incontiguous relationship with the poles of the magnet and defining aprimary air gap; a second pair of pole pieces disposed in contiguousrelationship with the first pair of pole pieces in the primary air gap,each of the second pole pieces forming a plurality of teeth, each of theteeth in one of the second pole pieces being disposed in opposingrelationship to an associated one of the teeth in the other of thesecond pole pieces to form one of a plurality of opposing tooth pairseach defining a secondary air gap; and each of the galvanometers beingassociated with one of the opposing tooth pairs with the coil of theassociated galvanometer being disposed in the associated secondary airgap..].
 17. The galvanometer assembly recited in claim .[.16.]. .Iadd.20.Iaddend.further comprising:a plurality of tubular members each mountedin a fixed relationship to the supporting structure with an associatedone of the coils disposed within an associated one of the tubular memberin a noncontiguous relationship with the associated tubular member; anda liquid disposed within at least one of the tubular members incontiguous relationship with the associated coil, the liquid having aviscosity for damping movement of the associated coil.
 18. Thegalvanometer assembly recited in claim 17 further comprising:a pluralityof centering wires each adhered to one of the second pole pieces andextending into contiguous relationship with an associated one of thetubular members for supporting the associated tubular member in thenoncontiguous relationship with the associated coil. .[.19. Thegalvanometer assembly recited in claim 14 further comprising:enclosuremeans forming a single cavity and the purality of suspensiongalvanometers being at least partially disposed within the single cavityof the enclosure means; and means for attaching the enclosure means tothe supporting structure means..].
 20. .[.The galvanometer assemblyrecited in claim 19 wherein the.].g A galvanometer assembly adapted foruse with a bipolar magnet in deflecting a light beam in accordance withthe characteristics of a plurality of signals to record the signals on aphotosensitive medium, including:a plurality of suspension galvanometerseach having an electrical coil adapted to receive an associated one ofthe signals and a mirror disposed in the path of the light beam andmovable with the associated coil to deflect the light beam in responseto the characteristics of the associated signal; supporting structuremeans for the plurality of galvanometers, said supporting structuremeans including a top fixture member and means for suspending theplurality of galvanometers from said top fixture member, with the coilsof the galvanometers disposed in substantially planar alignment; a firstpair of pole pieces disposed in contiguous relationship with the polesof the magnet and defining a primary air gap; a second pair of polepieces disposed in contiguous relationship with the first pair of polepieces in the primary air gap, each of the second pole pieces forming aplurality of teeth, each of the teeth in one of the second pole piecesbeing disposed in opposing relationship to an associated one of theteeth in the other of the second pole pieces to form one of a pluralityof opposing tooth pairs each defining a secondary air gap; each of thegalvanometers being associated with one of the opposing tooth pairs withthe coil of the associated galvanometer being disposed in the associatedsecondary air gap; enclosure means forming a single cavity and theplurality of suspension galvanometers being at least partially disposedwithin the single cavity of the enclosure means; and means for attachingthe enclosure means to the supporting structure means; enclosure means.[.includes.]. .Iadd.including .Iaddend.a single windowpane throughwhich the light passes to and from the mirrors of the galvanometers. 21.A galvanometer module, including:a supporting structure including afirst .[.structural.]. .Iadd.top fixture .Iaddend.member having alongitudinal configuration, and a .[.second structural.]. .Iadd.bottomfixture .Iaddend.member having a longitudinal configuration andincluding at least portions thereof disposed in spaced relationship withthe .[.first structural.]. .Iadd.top fixture .Iaddend.member; at least apair of galvanometers suspended between the .[.first structural.]..Iadd.top fixture .Iaddend.member and the portions of the .[.secondstructural.]. .Iadd.bottom fixture .Iaddend.member; enclosure meanscoupled to the supporting structure and defining a single cavity; andthe galvanometers being at least partially suspended by the supportingstructure in the single cavity of the enclosure means.
 22. .[.Thegalvanometer module of claim 21.]. .Iadd.A galvanometer module,including:a supporting structure including a first structural memberhaving a longitudinal configuration, and a second structural memberhaving a longitudinal configuration and including at least portionsthereof disposed in spaced relationship with the first structuralmember; at least a pair of galvanometers suspended between the firststructural member and the portions of the second structural member;enclosure means coupled to the supporting structure and defining asingle cavity; and the galvanometers being at least partially suspendedby the supporting structure in the single cavity of the enclosure means;wherein each of the galvanometers .[.includes.]. .Iadd.including.Iaddend.a mirror for reflecting a beam of light, and the enclosuremeans .[.includes.]. .Iadd.including .Iaddend.a single windowpanethrough which the beam of light is directed onto the mirrors and fromwhich the beam of light is reflected from the mirrors.